Technical Field
The present disclosure relates to a radar system.
Background
Recently, driver assistance safety systems are proposed in which a radar device adapted to detect an object around a host vehicle and an imaging device that images an image around the host vehicle are installed in a vehicle, and based on information detected by the radar device and the imaging device, control the vehicle to prevent an occurrence of a collision with other vehicles, etc., and to mitigate damages in case of a collision. As a method for implementing such a system, for example, H.-L. Bloecher et al., “79 GHz UWB automotive short range radar-Spectrum allocation and technology trends”, Adv. Radio Sci., 7, PP. 61-65, 2009 proposes a technical concept of sensing all orientations of a vehicle with a radar.
Further, for example, techniques disclosed in Japanese Examined Patent Publication No. 5-51870 and Japanese Laid-open Patent Publication No. 2003-107151 are known as techniques of providing a plurality of radar devices or imaging devices, and detecting an object based on signals from these plurality of radar devices or the like.
When a pulse radar is used as a radar device, a variation in temporal difference between transmission and reception at the radar causes an error in range measurement, and thus, it is necessary to remove factors causing the variation as much as possible. For example, in a case where the temporal difference between transmission and reception is in a nano-second order as in a short range radar, it is necessary to strictly control factors affecting the temporal difference between transmission and reception at the radar.
According to the technique disclosed in Japanese Examined Patent Publication No. 5-51870, pulse generating units and pulse receiving units of radar devices are provided as a common mechanism, and signals from a plurality of sensor sections are received unchanged as high frequency signals by the common mechanism. In this configuration, since the pulse receiving unit, which is a high frequency signal receiving unit, is provided in the common mechanism, a distance between an antenna and the pulse receiving unit also affects the temporal difference between transmission and reception at the radar. In other words, in order to solve the problem using the technique disclosed in Japanese Examined Patent Publication No. 5-51870, it is necessary to carry out a complicated management including management of the cable length between the radar devices and temperature management of the radar devices and the cables. Also, in a case where the distance between an antenna and a pulse receiving unit is long, there may be a case where a pulse waveform deforms under an influence of a transmission delay due to a cable between radar devices, and this may also become a degradation factor of a performance as a short range radar.
According to the technique disclosed in Japanese Laid-open Patent Publication No. 2003-107151, a plurality of sensor devices are controlled by a command control device. With such a configuration, an output from each of a plurality of sensor devices is transmitted to a command control device after being subject to signal processing, and thus power consumption as a radar system is large. Furthermore, Japanese Laid-open Patent Publication No. 2003-107151 discloses transmitting an output of a receiver unchanged to the command control device via a radio communication means, and since an output of the receiver is a video signal, when the wireless communication means is replaced with a wire transmission means, it becomes similar to the technique described in the aforementioned Japanese Examined Patent Publication No. 5-51870. Accordingly, it has a problem that a temporal difference between transmission and reception of the radar and a pulse waveform are affected.
Accordingly, the present disclosure is related to providing a radar system that can perform management of a temporal difference between transmission and reception and a pulse waveform of a high frequency signal from each of a plurality of radar devices in a facilitated manner such that an influence of a change in an operating environment is decreased and a power consumption of the system is reduced.